Work Questions

1. A man pushes on the wall of a building with force F.

a) How much work is done by the man?
b) How much work per second is done by the man according to a person moving with a velocity v away from the wall?
c) Does the kinetic energy of the wall increase due to this work? If not, explain why not.

2. A brick is resting on a concrete surface. Which of the following is true? I. the force required to overcome static friction is greater than the force required to overcome dynamic friction; II. the force required to overcome dynamic friction is greater than the force required to overcome static friction; III. friction is proportional to the component of weight acting normally on the surface
 a) all are correct
 b) I and II are correct
 c) I and III are correct
 d) II and III are correct

3 Compared to the amount of energy required to accelerate a car from rest to 10 miles per hour, the amount of energy required to accelerate the same car from 10 mph to 20 mph is

a) the same.
b) twice as much.
c) three times as much.
d) four times as much.

4. A puck moving across a horizontal surface experiences constant negative acceleration due to friction, and comes to rest after 12 seconds. How does the energy lost in the first 6 seconds compare to the energy lost in the last 6 seconds?

a) first half > second half
b) first half = second half
c) first half < second half
d) too little information